Carbon blends for enhanced gas storage

ABSTRACT

Containers for releasing pressurized contents that include adsorbent such as, for example, mixtures of activated carbons from different sources are described herein.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of U.S. Provisional Application No. 61/721,293, filed Nov. 1, 2012, the contents of which are incorporated herein in their entirety as if set forth herein.

GOVERNMENT INTERESTS

NOT APPLICABLE

PARTIES TO A JOINT RESEARCH AGREEMENT

NOT APPLICABLE

INCORPORATION BY REFERENCE OF MATERIAL SUBMITTED ON A COMPACT DISC

NOT APPLICABLE

BACKGROUND

Hydrocarbon or hydrofluorocarbon gases are used for various applications such as refrigeration, air conditioning and aerosol propellancy to name a few. Items containing hydrocarbon gases are prevalent in aerosol propellants and for releasing a product such as shaving gels or creams or generating a sound such as with noise makers or signaling horns. However, hydrofluorocarbon (HFC) gases have very high Global Warming Potentials (GWPs). Thus, the usage of HFCs in aerosols is mostly limited to products which require non-flammable or non-toxic propellants. Hence, items employing hydrocarbon gas may be inherently dangerous, the inappropriate use of which can result in serious accidents and fatalities. Even where the propellant is contained in an aerosol can, and is not released to the environment during use, when the used can is disposed and the containment ruptured or oxidized, the propellant will be ultimately released to atmosphere. To minimize hydrocarbon release, governmental authorities are considering restriction in the use of hydrocarbon and hydrofluorocarbon gases.

SUMMARY OF THE INVENTION

NOT APPLICABLE.

DESCRIPTION OF DRAWINGS

In the following detailed description, reference is made to the accompanying drawings, which form a part hereof. In the drawings, similar symbols typically identify similar components unless context dictates otherwise. The illustrative embodiments described in the detailed description, drawings, and claims are not meant to be limiting. Other embodiments may be utilized and other changes may be made, without departing from the spirit or scope of the subject matter presented herein. It will be readily understood that the aspects of the present disclosure, as generally described herein and illustrated in the figures, can be arranged, substituted, combined, separated, and designed in a wide variety of different configurations, all of which are explicitly contemplated herein.

FIG. 1 is a graph comparing CO2 uptake (g/liter) for carbons having activity levels from 27% CTC to 111% CTC at pressures of from 0 bar to 20 bar to CO2 concentration for compressed CO2.

FIG. 2 is a graph comparing CO2 uptake c (g/liter) for high activity activated carbon (111% CTC) to low activity activated carbon (57% CTC) at pressures from 0 bar to 14 bar.

FIG. 3 is a graph illustrating the effect of bulk density (g/cc) to CO2 adsorption (g/liter).

FIG. 4 is an illustrative container for dispersion of a liquid using a sorbent.

FIG. 5 is a graph comparing uptake of CO2 to uptake of nitrogen (N2) gas by low activity activated carbon (57% CTC) at pressures from 0 bar to 20 bar.

FIG. 6 is a graph comparing CO2 uptake (g/100 cc) of high activity, coconut based activated carbon (CNS), low activity, coal bases activated carbon, and a 50:50 blend of CNS and coal based activated carbon.

FIG. 7 is a graph showing the CO2 release (deliverable CO2) from activate carbon blends of CNS and coal based activated carbon having from 0% coal based activated carbon to 100% coal based activated carbon.

FIG. 8 is an illustrative container for releasing pressurized contents.

FIG. 9 is an illustrative container for releasing pressurized contents.

FIG. 10 is an illustrative container for releasing pressurized contents.

FIG. 11 is an illustrative container for releasing pressurized contents.

DETAILED DESCRIPTION

Before the present compositions and methods are described, it is to be understood that this invention is not limited to the particular processes, compositions, or methodologies described, as these may vary. It is also to be understood that the terminology used in the description is for the purpose of describing the particular versions or embodiments only, and is not intended to limit the scope of the present invention, which will be limited only by the appended claims. Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art. Although any methods and materials similar or equivalent to those described herein can be used in the practice or testing of embodiments of the present invention, the preferred methods, devices, and materials are now described. All publications mentioned herein are incorporated by reference in their entireties. Nothing herein is to be construed as an admission that the invention is not entitled to antedate such disclosure by virtue of prior invention.

It must also be noted that as used herein and in the appended claims, the singular forms “a,” “an,” and “the” include plural reference unless the context clearly dictates otherwise. Thus, for example, reference to “a combustion chamber” is a reference to “one or more combustion chambers” and equivalents thereof known to those skilled in the art, and so forth.

As used herein, the term “about” means plus or minus 10% of the numerical value of the number with which it is being used. Therefore, about 50% means in the range of 45%-55%.

Embodiments described herein are directed to containers including activated carbon or another sorbent material, and in particular embodiments, the containers may include a combination of activated carbon that provides improved absorbance over conventional containers including activated carbons. Such containers may include a material such as, but not limited to, air or another gas such as carbon dioxide, a liquid, gel, foam, or semi-solid material, that can be discharged from the container when a valve into the container is opened. Pressure on the inside of the container sufficient to expel the material through the valve may be provided by action of adsorbed gas released from the activated carbon or other adsorbent material. As such, the activated carbon or activated carbon blends of various embodiments may provide aerosol propellants that do not require hydrocarbons as well as an environmentally friendly means for releasing a product such as, for example, a liquid spray, gel, foams, cream, pastes, and the like or a gas for medical devices or for generating a sound.

While any adsorbent material may be used in the containers encompassed by the invention, in some embodiments, the sorbent material may be activated carbon. Activated carbon for use in such containers can be prepared from carbon sources including, among others, natural carbonaceous sources, such as peat, wood, coal, nutshell (such as, coconut, walnut, and the like), petroleum coke, bone, bamboo shoot, drupe stones, various seeds, and synthetic sources, such as poly(acrylonitrile) or phenol-formaldehyde. The carbon is activated to develop an intricate network of pores and surface area sufficient for adsorption. The pores can have various sizes. Generally, larger transport pores provide access to the smaller pores in which most of the adsorption of propellant takes place. Carbon activation can be conducted at elevated temperatures with gaseous activation using steam, carbon dioxide, or other gases, or chemical activation can be conducted using, for example, zinc chloride or phosphoric acid. Other activation processes may be used to achieve the pore structure and surface area that provides an extensive physical adsorption property and a high volume of adsorbing porosity. The activated carbon used in embodiments can be in any form including, for example, powdered, granular, or pelleted activated carbon or activated carbon in the form of a cloth, felt or fabric. In particular embodiments, granules or pellets can be used to decrease dust generation during manufacture and/or assembly.

In some embodiments, the activated carbon can be prepared using methods that provide a relatively high prevalence of micropore shaving an average pore diameter of about 0.5 nm to about 2.5 nm, or in other embodiments, the activated carbon may include a high proportion of pores having an average pore diameter of about 1.0 nm to about 2.0 nm. In certain embodiments, the activated carbon may have a low enthalpy of adsorption, for example, less than about 25 kJ (mole of adsorbate)−1, less than about 20 kJ (mole of adsorbate)−1, less than about 15 kJ (mole of adsorbate)−1, less than about 10 kJ (mole of adsorbate)−1, or any range within these exemplary maxima including, but not limited to, about 2 kJ (mole of adsorbate)-1 to about 25 kJ (mole of adsorbate)−1, about 4 kJ (mole of adsorbate)-1 to about 20 kJ (mole of adsorbate)−1, about 5 kJ (mole of adsorbate)-1 to about 15 kJ (mole of adsorbate)−1, or any range therebetween. In particular embodiments, the activated carbon may have a combination of these properties, for example, a high concentration of micropores and a low enthalpy of adsorption (for the propellant gas).

Activated carbon provides significantly higher concentration gas storage than compressed gas alone. The degree of CO2 uptake on activated carbon is normally regarded as a function of the level of activity to which the carbon has been subjected. The percentage activity (% w/w) of the activated carbon is measured in terms of its ability to adsorb carbon tetrachloride (CTC) by saturating the carbon's pores with CTC. A more highly active activated carbon will have a higher percent activity than a lower activity activated carbon. More highly activated carbons show an increased propensity to adsorb carbon dioxide, which could be due to increases in microporosity and surface area. FIG. 1 compares concentration (g/liter) of CO2 when adsorbed on coconut-based activated carbon to the concentration of compressed CO2 at various pressures and shows that activated carbon at all activity levels provides a higher concentration of CO2 at all pressures than compressed CO2 alone including pressures compatible with the common aerosol-type containment devices (4 bar to 16 bar, 40000 Pascal to 1600000 Pascal). For fixed volume containment such as is the case in an aerosol-type can, higher concentration containment may allow for improved delivery of CO2.

FIG. 2 compares a low activity coconut based activated carbon (57% CTC) with a high activity coconut based activated carbon (111% CTC). At relatively low pressure, the low activity activated carbon provides higher concentration CO2; however, at high pressure, e.g., greater than about 10 bar absolute (1000000 Pascal), higher activity carbon shows improved uptake and can attain a higher CO2 concentration. This appears to suggest that bulk density (g/cc) effects uptake and adsorption of CO2 as a function of the pressure. FIG. 3 graphically illustrates the relationship of bulk density to CO2 adsorption and shows that CO2 adsorption increases approximately linearly with increase in bulk density.

Adsorbency also varies among activated carbons depending on source materials used to produce the activated carbon. For example, nutshell, and in particular, coconut based activated carbon generally exhibits higher volumetric activity (0.16 g/cc butane) than coal based activated carbon exhibiting volumetric activity (0.14 g/cc butane). Like FIG. 2 above, FIG. 6 shows that higher volumetric activity coconut based activated carbon (“CNS,” ∘) provides higher concentration of carbon dioxide than more common lower activity coal-based activated carbon (“Coal,” ▪) at all pressures tested. Surprisingly, a combination of CNS and Coal (“50:50 Blend,” ▴) appears to provide a nearly equal concentration of CO2 as higher activity activated carbon.

In addition to approximately equal adsorption, blends of low activity and high activity activated carbon show improved delivery of adsorbed CO2. As illustrated in Table 1 and FIG. 6, adsorption of CO2, i.e., CO2 uptake, decreases as the fraction of coal based activated carbon is increased in various activated carbon blends. Surprisingly, the CO2 discharge, i.e., deliverable CO2, stays constant or increases as the fraction of coal based carbon is increased. For example, discharge from 100% CNS was measured as 15.7 g/100 cc and discharge from 100% coal based activate carbon was 14.5 g/100 cc. Notably, discharge from a 50:50 blend of CNS and coal based activated carbon was measured at 15.8 g/100 cc. Accordingly, without wishing to be bound by theory, discharge from a blend of CNS and coal based activated carbon may provide at least equal CO2 discharge as CNS, and in some cases, greater discharge than high activity carbon alone.

While the activated carbon used in embodiments of the invention may be produced from any carbon source known in the art, in certain embodiments, the sorbent may be activated carbon produced from nutshell or coconut. In other embodiments, the sorbent may be a combination or blend of activated carbon produced from coconut and coal. The coal used in such embodiments may be of any rank including anthracite, semi-anthracite, bituminous, sub-bituminous, brown coals, or lignites, and the blends may include any amount of nutshell and coal based activated carbons. For example, in various embodiments, the sorbent may be about 90% to about 40% coconut and about 10% and about 60% coal.

Any gas that may be adsorbed onto activated carbon can be used in various embodiments of the invention including, but not limited to, hydrogen, nitrogen, oxygen, carbon dioxide, argon, propane, butane, and the adsorbed gas may be a pure form of the gas or a combination of various gases. In general, the use of activated carbon allows for a greater volume of gas to be stored at lower system pressures than would be possible for an equivalent volume compressed gas.

Including activated carbon in containers of compressed gas provides a number of benefits including, for example: (1) smaller, more portable size containers resulting from the increased capacity of oxygen or other gas in the container, (2) extraneous odors associated with the product within the container can be retained by the activated carbon, (3) improved static (physical) equilibrium within the container, (4) improved efficiency and uniform delivery of the gas from the can as the contents are depleted, and (5) improved storage capacity of compressed gas. Typically, a vessel fitted with activated carbon can store 3 times more compressed air than, for example, a classical air vessel. As a consequence, the load on the compressor is itself reduced.

The sorbent blends described above may be used for any application where high volume discharge of sorbate from the sorbent is necessary. For example, in some embodiments, the sorbent blends may be used in containers for discharge of pressurized contents. Such containers are known in the art and generally include a container configured and designed to hold a sorbent material and a product to be discharged.

In some embodiments, the stored gas may be oxygen. The inhalation of pure oxygen from conveniently sized containers is practiced for athletic enhancement, therapeutic, medical, cosmetic, and other reasons and has been purported to alleviate stress and anxiety, cure headaches, hangovers and jetlag, improve memory, and provide a feeling of general well-being. In particular, mountaineers use oxygen canisters at high altitude where the oxygen content of the air is low, drivers use compressed oxygen to combat drowsiness, and athletes use compressed oxygen to improve performance and aid in recovery. Medical uses for compressed oxygen are wide spread and include combating lung disease by increasing blood oxygen levels and to speed recovery after surgery, and oxygen is also applied locally to the skin to aid adsorption of creams and lotions into subcutaneous layers.

In embodiments in which the gas is inhaled, the container may include an adapter piece in the form of, for example, a mask, mouth piece, nose piece or combinations thereof, for fitting over the mouth and/or nose of the user. Such an arrangement would enable the gas, such as oxygen or air, to be breathed in by the user for medical reasons or, for example, to avoid inhalation of smoke or other chemicals. In some embodiments, the adapter may be provided with a series of holes to enable the adapter to be flushed with the stored gas prior to the user breathing in the gas.

In other embodiments, the container may include carbon dioxide. Carbon dioxide can have an extraordinarily high uptake on activated carbon. For example, as much as about 250 g/liter of carbon has been recorded at 16 bar gauge pressure (1600000 Pascal) where the corresponding compressed gas weight would be only 29 g/liter. Such high-density gas storage may be employed for all manners of application, particularly for an innocuous, non-flammable, low toxicity, and environmentally neutral material such as, for example, aerosol propellants, working fluids, and pressure regulating devices.

In certain embodiments, CO2 adsorbed on activated carbon blends may be used in containers for dispensing fluid. Thus, some embodiments include systems for delivery of carbonated beverages. For example, embodiments include a bag-in-can system, as illustrated in FIG. 4. The can may be of any volume, and in certain embodiments, may be a large volume can, for example, 5 liters. In some embodiments, such containers may include an enclosure 12 made from plastic or another flexible material containing beer or other carbonated beverage within a container 10. A dip-leg 18 may extend from an actuating valve 20 into the enclosure 12 and may allow beverage to be dispensed from the enclosure when the actuating valve 20 is opened through a dispensing tube 22.

A space 24 surrounding the plastic enclosure is filled with carbon dioxide adsorbed on activated carbon, and a grommet 16 may be provided on the container for introducing activated carbon into the container. In some embodiments, the activated carbon may be pre-saturated with carbon dioxide, and additional carbon dioxide can be charged to the container before the container 10 is sealed. In other embodiments, solid CO2 or dry ice may be introduced into the container 10 along with the activated carbon, and in still other embodiments, both gaseous CO2 and solid CO2 (dry ice) may be incorporated into the container before it is sealed. Solid CO2 or dry ice has been found to counteract any exothermic reaction during adsorption, which may be important for large volume containers where repeated cooling and charging of the can could otherwise be required to avoid overheating the contents of the enclosure.

The device of such embodiments may provide a smooth flow of beverage during discharge and may allow for complete discharge of the contents of the enclosure 12. The beverage also remains in a fresh and carbonated condition because the volume of the bag enclosure tracks the volume of the remaining liquid and no gas headspace is generated. Thus, little carbonation is lost during discharge of the beverage. In addition, compressed gases require excessive pressures to accommodate the volume of gas required to discharge the contents of the bag completely, and there is a rapid reduction in pressure when compressed gas is used to expel the contents of such enclosures. Thus, too much of the product is discharged at initial actuation and too little discharged as the enclosure empties. In contrast, adsorbed carbon dioxide gives only a small, almost indiscernible, pressure decrease as the product is discharged resulting in a steadier flow of product. Hence, although the total volume of gas required for dispensation of the product is the same both for compressed gas and adsorbed gas, the delivery profile is very different. The important parameter is the volume of gas delivered per unit of pressure drop.

In some embodiments, the blend of activated carbon may further transfer heat to or from a liquid within the container. In such embodiments, the blend of activated carbon may be combined with a graphite material such that the activated carbon is about 0.01% to about 80% by weight of the total composition. In further embodiments, a binder may further be included in the mixture of activated carbon and graphite.

Any available form of graphite, natural or synthetic, may be incorporated into the composition of such embodiments, and the graphite can be in any form including, for example, a powder or flakes. In some embodiments, the graphite may be from about 10% to about 50% by weight, about 20% to about 45% by weight or, in certain embodiments, about 40% by weight of the total composition. Without wishing to be bound by theory, the inclusion of graphite with the activated carbon blend may increase the rate of transfer of heat from the material to its surroundings over the rate of heat transfer by activated carbon alone. The transfer of heat away from the product within a container may cause the product to cool by this action in the absence of another cooling means such as refrigeration. Therefore, in the context of a beverage, the activated carbon blend may provide increased self-life by maintaining constant pressure on the product and eliminating air from the container while simultaneously cooling the product.

The binder material may be any binder material known in the art including, for example, poly(tetrafluoroethylene), and the binder may be provided in an amount sufficient to achieve densification of the formulation. Thus, the composition may be provided in the form of a monolith or block, and in containers, the composition may be in the form of a continuous cylindrical block. Without wishing to be bound by theory, providing the formulation in a solid, block form, may assist in heat transfer due to the absence of voids between the carbon particles. Mechanical manipulation of the block or monolith may be carried out, for example, by drilling holes into the block, to enhance gas transfer by increasing the surface area from which the gas can escape further enhancing the cooling effect.

Any gas that can be adsorbed by activated carbon may be stored in a low pressure container according to the present invention. In certain embodiments, adsorbed nitrogen may be used in place of carbon dioxide for use as an aerosol propellant or pressure regulating device in which it may be preferable to use nitrogen because, for example, nitrogen may be more environmentally friendly or less permeable to certain types of plastic enclosures. However, more activated carbon may be required to adsorb a similar quantity of nitrogen relative to carbon dioxide at a given pressure. As illustrated in FIG. 5, activated carbon having the same activity level (57% CTC) may adsorb more CO2 than nitrogen (N2) over a broad range of pressures.

Embodiments also include containers including the activated carbon blends described above and a compressed gas. In some embodiments, such containers may include at least a first compartment. The first compartment may be configured to enclose the sorbent material and a propellant. In some embodiments, the product to be dispelled from the container may also be included in the first compartment and may be separated by a physical barrier, such as, for example, a bag or bladder as illustrated in FIG. 9 and FIG. 10, or a piston as illustrated in FIG. 11 from the sorbent and propellant. In other embodiments, as illustrated in FIG. 8, the sorbent material and product to be discharged can be combined in the first compartment. Such containers are generally designed for the discharge of a gas for use, for example, in pressurized dusters, medical devices, and noisemaking devices. The stored product can consist of any one or more of a variety of products including, among others, hairsprays, deodorants, insecticides, air fresheners, cleaning products, and so on, as well as materials of higher viscosities or different rheologies, such as adhesives, sealants, lubricants, mastics, paint, food products, and novelty products such as “silly string,” and the like. In certain embodiments, the product may be methane or natural gas, for diurnal storage or as a gasoline replacement in automobiles. In other embodiments, the product may be a liquid such as a beverage. In some embodiments, the activated carbon may adsorb a refrigerant gas such as, for example, carbon dioxide, which, when released from the activated carbon, can be used to produce refrigeration that can be used to chill, for example, a beverage can.

FIG. 9 shows an exemplary container including activated carbon, a sorbent, or a combination thereof. In such embodiments, a container 10 having a first compartment 12 adapted to accommodate a bladder 30 and adsorbent material 16 such as, for example, a blend of nutshell activated carbon and coal based activated carbon. The product to be dispensed 32 may be disposed within the bladder 30. The bladder 30, of such embodiments, may be composed of any pliable airtight material and will generally have the strength and permeability characteristics appropriate for the product 32 and the propellant. For example, in embodiments in which the propellant is CO2, the bladder may be composed of a material that has a low permeability of CO2 for example. In particular embodiments, the bladder 30 may be composed of a plastic or other flexible polymer or a metal such as, for example, aluminum, and in certain embodiments, the bladder 30 may be a 3- or 4-pouch aluminized bag.

The first compartment may further include compressed air, or in some embodiments, the first compartment 12 may include a propellant gas such as, but not limited to, air, oxygen, nitrogen, carbon dioxide, a noble gas, such as helium, neon, argon, krypton, xenon, nitrous oxide, or a combination thereof. In certain embodiments, the propellant may be carbon dioxide or nitrous oxide. Different gases provide different uptakes, different heels and different deliverable volumes of gas because of the different interaction potentials between the adsorbed gas and adsorbent. In certain embodiments, in which carbon dioxide is used as the propellant, the carbon dioxide can be either a gas or a solid. In general, the propellant may be provided in sufficient quantity to meet the maximum adsorption capacity of the sorbent. In some embodiments, the air or propellant may be provided in a quantity to pressurize the first compartment, and in particular embodiments, the maximum pressure in a container including a sorbent material may substantially equal the pressure of containers including only compressed gas and no sorbent. For example, in various embodiments, the air or propellant may be provided in sufficient quantity to produce a pressure of about 1 barg to about 15 barg, about 2 barg to about 12 barg, about 5 barg to about 10 barg, or any individual value or range encompassed by these exemplary ranges.

In some embodiments, the container may include a valve 18 having at least one conduit extending into the bladder 30 that provides a release channel for discharging product 32 from bladder 30. Any valve type known in the art may be used in various embodiments. For example, in some embodiments, the valve 18 may operate by aligning one or more openings on a valve stem to allow flow of material through the openings. The number and effective area of orifices on the valve stem can vary among embodiments. In particular embodiments, one or more orifices having a larger effective area may deliver a more powerful blast, i.e., a high volume expulsion, than one or more orifices having a smaller effective area; however, the high volume expulsion may deplete propellant more quickly.

In certain embodiments, the container may include an actuator 20 disposed on an outer surface of the container 10, and the actuator is capable of causing the valve 18 to open when the actuator is activated, and a spring associated with the actuator 20 that allows the actuator to return to its original position thereby closing the valve. In some embodiments, the valve 18 may further include a male or female fitting that allows for a reversible connection to the actuator. Thus, the fill bladder 30 may be filled or refilled with a product through the valve when the actuator is removed, and the actuator can be replaced to facilitate dispersion of the product. In certain embodiments, the container may further include a regulator capable of regulating the flow of propellant or product through the valve, and the regulator may provide a fixed rate for delivery or may be adjustable such that the flow rate for propellant or product can be modified.

In operation, the actuator 20 may be depressed allowing gas adsorbed on the sorbent material 16 to be released causing the volume gas in the first compartment 12 to expand and increasing the pressure in the container. The increased pressure forces the product 32 in the bladder 30 to be expelled from within the bladder 30 through the conduit where it is dispensed from the container. When the actuator 20 is released, the valve 18 closes stopping the release of gas from the sorbent material and stopping the flow of product from the bladder 30. In embodiments in which a bladder is provided within the container, the air or propellant is not released from the container, but the pressure inside the container may decrease as the volume of the first compartment increases as a result of the reduced volume of the bladder following dispersion of the product.

Generally, the sorbent material 16 may be disposed in a portion of the first compartment 12. The sorbent may be provided in any amount sufficient to achieve the desired pressure for anticipated use. The amount of sorbent used is, typically, a function of the initial pressure, the target final pressure, the volume of the can, and the volume of the bladder. In addition, the target pressure may depend upon the characteristics of the product 32 to be dispensed, for example, viscosity or density of the product, and the desired flow rate of the product as it is dispensed. The target pressure can be determined by using weight combinations of carbon and propellant gas that will yield a generally consistent discharge rate and provide a pressure and a flow rate from the can that is indiscernible for the user from start to finish. Thus, the amount of sorbent used should be calculated to minimize the difference between the initial pressure and the pressure after discharge of the product, P. For example, the P may be less than about 2 bar, or in certain embodiments, less than about 1 bar.

As illustrated in FIG. 10, in some embodiments, an adsorbent pad 40 may be provided in the first compartment 12 between the bladder 30 and carbon material 16. The pad 40 may generally be positioned to reduce contact of the carbon material with the product 32 in the event that the bladder 30 leaks. The pad 40 may be composed of any material and, in certain embodiments, maybe constructed of material appropriate for the absorption of the product contained in the bladder 30.

In some embodiments, the container may be designed for the release of gas to produce, for example, an air horn or compressed air duster. As illustrated in FIG. 8, in such embodiments, the container may not include a bag, and the first compartment may be completely or nearly completely filled with sorbent and propellant. Such containers may include a valve 18 and actuator 20 system for release of the propellant similar to those described above with regard to FIG. 3. In some embodiments, the valve 18 may be fitted with a valve dip tube and a filter device 19 capable of removing carbon dust from the dispensed gas. The first compartment 12 may be charged with a propellant or air to a pressure of about 1 barg to about 15 barg. In operation, opening the valve 18 by action of the actuator 20 may cause release of the propellant from sorbent 16, through the valve, and into the atmosphere.

The container may be designed to have a shape and size appropriate to accommodate a suitable pressure level for the select application. In some embodiments, the container 8 can be designed to resemble a standard aerosol-type can and can be fabricated from tin plate or aluminum. In other embodiments, the container can be made from plastic material when relatively low pressures compared to that for compressed gas without carbon are used. For example, a molded plastic can be used for containers for dispensing soap and shave gel, which require up to about 5 barg for dispersion. In certain embodiments, containers including a product that would generally require higher pressure for adequate dispersion may be made from a plastic material. Without wishing to be bound by theory, the additional gas can be introduced into containers including a sorbent material, because a portion of the gas is adsorbed on the sorbent allowing a greater volume of released gas than for containers that include compressed gas alone. Such containers may allow for long-term low-pressure dispersion of a product that would otherwise have required high initial pressure of compressed gas, and this lower pressure might enable use of a plastic container. The plastic containers, of various embodiments, can be molded into any shape, for example, square or rectangular or other convenient shape for efficient packing and transportation in bulk.

Other embodiments are directed to containers that include a piston. For example, FIG. 11, show containers 110 having a first compartment 112 having a first chamber 122 that is separated from a second chamber 124 by a piston 113. In such embodiments, the first chamber 122 may be designed to hold a sorbent material 116 and a propellant gas, and in particular embodiments, the first chamber may be charged to a pressure of about 1 to 15 barg. The second chamber 124 may be designed to hold product 132. The container 110 may further include, for example, a valve, valve housing 118, and delivery tube 120 for releasing product 132. Alternative mechanisms may be used for effective release of product, such as the valve 18 and actuator 20 system as described above in relation to FIG. 8.

The piston 113 can be constructed of any material such as, for example, plastic material such as polypropylene or other polymers or polymer blends. The piston 113 may have any shape. For example, in some embodiments, the piston may be any open cylinder, which may further include a cylindrical stem. In general, the sorbent and propellant may be contained within the cylinder, and in some embodiments, the sorbent and propellant may be provided in a gap between the base of the container and the bottom of the piston. The carbon may be introduced into the container in any way. For example, the carbon and propellant can be introduced into the container through an opening 140 in the base of the container, and in other embodiments, the piston may be inserted into the container over the sorbent and propellant, which were introduced into the container before the piston. As described above, the amount of sorbent and propellant may be an amount sufficient to provide sufficient pressure to the piston to effectuate release of the product 132 from the second chamber 124.

In operation, the valve housed within valve housing 118 may be depressed releasing the product 132 through the delivery tube by force of the propellant on the piston. The volume of the first chamber increases as the piston moves into the second chamber, the product is dispensed, and propellant adsorbed onto the carbon material 116 filling any void and continuing to pushing piston 113 through the second chamber.

In various embodiments described above, the product can be stored in an enclosure or otherwise separate from the sorbent material. In conventional aerosol cans, the propellant such as a hydrocarbon or hydrofluorocarbon, is mixed with the product, and upon actuation of the valve, the propellant is released to the environment along with the active product. The bladder 30 enables release of the product without the discharge of propellant because the activated carbon/gas material remains enclosed within container.

Other embodiments are directed to methods for replacing hydrocarbon propellants with a sorbent material including a blend or mixture of activated carbon from nutshell and coal feedstocks. For example, some embodiments include the steps of filling or substantially filling a sealable container with a blend or mixture of activated carbon from nutshell and coal feedstocks, applying a stream of compressed gas into the container for adsorption by the carbon, and sealing the container. Gas may be applied for adsorption into the carbon pores until reaching equilibrium pressure. For example, a regulated compressed gas cylinder may be connected to the can and admitted until the can reaches the regulated pressure. In certain embodiments, the activated carbon may be exposed to the compressed gas several times such that each exposure brings the container closer to the equilibrium pressure. In some embodiments, gas or compressed gas can be added through a valve or opening into the container.

In other embodiments, the gas can be added by applying a liquid or a solid form of the propellant gas into the container for adsorption by the carbon blend. Such methods may include filling the container with the blend or mixture of activated carbon from nutshell and coal feedstocks, adding solid CO2, inserting a bag-on-valve into the container, and crimping the bag-on-valve on the container. Crimping can be accomplished, for example, by use of a device that forces a ring containing the valve onto a neck of the can and crimping the two together.

EXAMPLES

Although the present invention has been described in considerable detail with reference to certain preferred embodiments thereof, other versions are possible. Therefore the spirit and scope of the appended claims should not be limited to the description and the preferred versions contained within this specification. Various aspects of the present invention will be illustrated with reference to the following non-limiting examples.

Example 1

Uptake of CO2 was determined for coconut based activated carbon, coal based activated carbon and a 50:50 blend of coconut and coal based activated carbons at 5° C. under pressures ranging from 0 to 12.5 barg.

To quantify the amount of carbon dioxide gas (100%) that is adsorbed by a measured mass of activated carbon (or a prepared blended mix of activated carbons) under selected equilibration conditions of positive pressure at a set point temperature, a weighed amount of activated carbon was introduced into a standard 200 ml internal volume aerosol that was then fitted with a crimped valve with a filter frit fitment. The carbon filled test can was flushed out five or six times with 5 barg pressurized 100% CO2 gas to remove air from the can/carbon system. The flushed test can was then cooled to 5° C., and 12 barg pressurized 100% CO2 gas until it was equilibrated between 10 and 11 barg pressure at 5° C. Re-weighing was used to determine the mass of CO2 in the equilibrated test can. By operation of the aerosol valve, an amount of CO2 gas was then released from the test can, and the can was immediately re-equilibrated to 5° C. At 5° C., the equilibrated can weight and can pressure was determined and recorded. An additional amount of CO2 gas was then released from the can. The can was re-equilibrated back to 5° C., and the can weight was determined and recorded. This procedure of determining the respective can weight and pressure properties, followed by some CO2 gas release and re-equilibration to 5° C. was repeated until the can system pressure was reduced to atmospheric pressure and no additional CO2 gas was released when the valve was opened.

The mass of CO2 adsorbed per 100 g of carbon was determined based on the weight of the can and can pressures, and these values were plotted as a function of can pressure at 5° C. The packing density (AD) of the carbon sample was calculated (g carbon per 100 ml) was also determined based on the measured weight of carbon in the 200 ml test can, and the corresponding values of g CO2 adsorbed per 100 ml of carbon was calculated and plotted as a function of system pressure.

The results are provided in FIG. 6, and show that a sample of 100% coconut based activated carbon has a higher volumetric activity than an equal amount of 100% coal based activated carbon. Surprisingly, CO2 uptake for a 50:50 blend coconut based activated carbon and coal based activated carbon was substantially the same as CO2 uptake for coconut based activated carbon alone at all pressures tested. These data suggest that the coconut based activated carbon and coal based activated carbon blend exhibits a similar volumetric activity to coconut based activated carbon despite the coal based activated carbon, which makes up 50% of the blend, having a lower volumetric activity.

Example 2

To further examine this phenomenon, various blends coconut based activated carbon and coal based activated carbon were prepared. CO2 uptake was measured at 10 barg and atmospheric pressure (atm), and the amount of CO2 expelled from the charged activated carbon was determined. The methods described in Example 1 were used to provide the results below.

The results are presented in Table 1 and a graphical representation of these data is presented in FIG. 7. Consistent with previous results, 100% coconut (CNS) exhibited improved CO2 uptake at both 10 barg and atm, 21.1 g/100 cc and 5.4 g/100 cc, respectively, over 100% coal (coal), 19.1 g/100 cc and 4.6 g/100 cc, respectively, Similarly, CNS delivered a greater amount of CO2 than coal, compare 15.7 g/100 cc and 14.5 g/100 cc. As expected, blends of CNS and coal show a consistent decrease in CO2 uptake as the amount of CNS decreases from 90% to 10% and the amount of coal in the blends increase from 10% to 90% at both 10 barg and atm, see columns 1 and 2. Notably however, the amount of CO2 delivered from blends of CNS and coal remained substantially the same (15.8 to 15.6 g/100 cc) for blends having up to 60% coal and 40% CNS. In fact, the amount of CO2 delivered from a 50:50 blend of CNS and coal may be greater than CNS alone. These data suggest a synergy between CNS and coal that allows for greater delivery of propellant despite lower uptake.

TABLE 1 CO₂ Uptake CO₂ Uptake Atm. Deliverable CO₂ 10 barg, 5° C. Pressure, 5° C. from 10 barg % CNS % Coal (g/100 cc) (g/100 cc) (g/100 cc) 100 0 21.1 5.4 15.7 90 10 21.0 5.3 15.7 80 20 20.9 5.2 15.7 60 40 20.8 5.1 15.7 50 50 20.8 5.0 15.8 40 60 20.4 4.8 15.6 20 80 20.0 4.7 15.3 10 90 19.7 4.7 15.0 0 100 19.1 4.6 14.5

Example 3

The cooling effect of a compacted activated carbon/graphite mixture was investigated by cooling a steel block to 55° C. using hydrated calcium chloride and ice. The surface of the steel block was then contacted by activated carbon and a binder, compositions including activated carbon, binder, and 10% or 30% by weight of graphite, or a compacted formulation containing activated carbon, binder, and 10% by weight of aluminum powder. A thermocouple in contact with the surface of the composition was used to measure the change in temperature of the compositions over time. Results are provided in Table 2:

TABLE 2 Temperature AC + 10% AC + 10% AC + 30% (° C.) AC Al Graphite Graphite Time taken to reach Temperature/seconds 23 — — — 9 22 25 — 25 37 21 55 40 33 59 20 80 60 45 70 19 97 80 66 85 18 115 100 85 95 17 130 115 100 106 16 147 127 120 115 15 165 142 130 127 14 182 155 145 135 13 200 171 160 149 12 219 186 177 158 11 240 199 192 169 10 260 213 210 183 9 282 231 227 195 8 308 251 248 208 7 338 267 268 221 6 372 287 290 237 5 415 315 315 254 4 465 340 345 270 3 525 374 376 290 2 — 407 417 310 1 — 462 470 335 0 — 525 — 364

These results show that a composition having 10% graphite has a similar cooling effect as a composition containing 10% aluminum, which is known to exhibit high thermal conductivity, with activated carbon. The composition containing aluminum was expected to show a more rapid cooling effect than the compacted composition containing an equivalent graphite admixture. The inclusion of 30% graphite enabled the compacted composition to reach a temperature of less than 10° C. more quickly than any of the other tested compositions thereby reducing the total length of time taken to obtain a satisfactory drop in temperature of a beverage contained within a can.

Example 4

The quantity of carbon dioxide gas adsorbed under pressurized conditions by compositions including activated carbon and graphite and the amount of carbon dioxide gas released from these compositions when gas pressure is vented was determined. Compositions included formulations of granular activated carbon mixed with 0%, 10%, and 30% graphite and poly(tetrafluoroethylene) (PTFE) binder. Test containers having a volume of 209 cm3 were filled to capacity with an activated carbon and graphite mixture, and a ram compression device operating up to 2.75 kN cm-2 (2 tons per square inch) was used to compact the mixture. The weight of the compacted mixture was recorded. A supply of compressed carbon dioxide gas was connected to the test container and gas was introduced into the container at ambient temperature. An increase in temperature of the container and contents due to the adsorption exotherm was observed. The containers were transferred to a cold bath at 0° C., and the compressed carbon dioxide connection was maintained at a pressure of 11 bar for 60 minutes until full gas uptake was achieved. The test containers were reweighed, and carbon dioxide uptake determined.

The pressurized container was left to attain ambient temperature, and the container was then vented to atmosphere. After 20 minutes, the vented container was reweighed to determine the amount of carbon dioxide released. Containers were left to attain ambient temperature and reweighed after approximately 16 hours following venting of gas. Results are provided in Table 3:

TABLE 3 CO₂ CO₂ Compact Uptake CO₂ Uptake Release 20 mins. CO₂ Density 10 mins., 0° C., post Release Sample Graphite % Binder % g/cm³ 19.5° C. 11 bar vent 16 hours 1 0 0 0.56 27.6 g 62.5 g 39.3 g 50.1 g 2 0 10 0.61 28.4 g 62.5 g 44.3 g 59.3 g 3 10 11 0.64 27.3 g 62.0 g  41.1 g* 55.8 g 4 30 12 0.71 27.3 g 59.7 g 42.5 g 57.7 g *calculated quantity

These data indicate that compacted compositions, including activated carbon and graphite, provide increased density compared to the control carbon. Carbon dioxide uptake values for the compositions were broadly similar to the control carbon and were not reduced pro-rata with graphite additions. However, carbon dioxide released by the compacted compositions on venting for 20 minutes were greater for the activated carbon graphite mixtures than control carbon, indicating that carbon dioxide was released at a slightly faster rate and that the compositions tested were less retentive.

Example 5

An additional series of compacted compositions containing activated carbon and 25%, 30%, 40%, 60%, and 80% graphite and PTFE binder were prepared, and the amount of carbon dioxide absorbed and released by these compositions were determined. The cooling effect from controlled pressure release of adsorbed carbon dioxide from these compacted was also determined. Results are provided in Table 4:

TABLE 4 Sample 5 6 7 8 9 AC 100 100 100 100 100 Graphite 25 30 40 60 80 Binder 12.5 13 14 16 18 Compact 139.5 g 144.0 g 158.8 g 171.4 g 181.8 g Weight g Compact 0.667 0.690 0.76 0.82 0.87 Density g/cm³ CO₂ Uptake 27.2 g 26.7 g 29.0 g 26.4 g 28.3 g 10 mins., 19.5° C. CO₂ Uptake 54.1 g 53.2 g 52.2 g 51.9 g 51.6 g 0° C., 12 bar CO₂ Release 38.2 g 38.0 g 39.9 g 39.8 g 40.3 g 20 mins. post vent Minimum −14.7 −14.9 −15.9 −12.9 −13.9 Temp. T⁰ _(min) (avg.) 4.1 4.6 4.1 6.1 4.1 Cooling Differential ° C. Time to 1.90 2.05 2.05 2.44 2.20 T⁰ _(min) minutes

These results indicate that each of the compacted compositions including activated carbon and graphite exhibited increased compressed density, which appears to correspond with the amount of graphite in the compositions. Carbon dioxide uptake values for the compacted compositions at 0° C. and 12 bar pressure reduced slightly with graphite content. However, carbon dioxide release on venting for 20 minutes remained fairly constant throughout independent of graphite proportion. 

What is claimed is:
 1. A container for dispensing pressurized contents comprising: a container having at least a first compartment; a blend of activated carbon comprising up to about 40% coal based activated carbon and about 60% nut based activated carbon contained within the first compartment; and a propellant contained within the first compartment, wherein at least a portion of the propellant is adsorbed onto the blend of activated carbon.
 2. The container of claim 1, further comprising a valve for releasing contents of the container.
 3. The container of claim 2, further comprising an actuator for opening and closing the valve.
 4. The container of claim 1, further comprising a bag for holding a product to be dispensed within the first compartment.
 5. The container of claim 1, further comprising a piston in the first compartment.
 6. The container of claim 5, wherein a piston is disposed between the blend of activated carbon and the propellant and a valve.
 7. The container of claim 1, wherein the nut based activated carbon is coconut based activated carbon.
 8. The container of claim 1, wherein the propellant is selected from the group consisting of air, noble gases, carbon dioxide, and combinations thereof.
 9. The container of claim 1, wherein the propellant is carbon dioxide.
 10. A method for dispelling contents of a container, the method comprising releasing adsorbed gas from a blend of activated carbon comprising up to about 40% coal based activated carbon and about 60% nut based activated carbon contained within the first compartment. 